Light reflector

ABSTRACT

A technology for effectively preventing deformation of a light reflector plate fabricated by forming a synthetic resin reflector plate into a three-dimensional shape enabling a thinner light reflector plate, and additionally, reducing processing costs is provided. An adhesive tape for shape-retention is adhered onto a reflector plate which is fabricated by forming predetermined areas of a light-reflecting plastic film or sheet into a three-dimensional shape.

TECHNICAL FIELD

The present invention relates a three-dimensional light reflector plateenabling brighter and thinner backlights and illumination boxes forillumination signboards, liquid crystal display devices, lightingfixtures, and the like.

BACKGROUND ART

Conventionally proposed light reflector plates for use in illuminationsignboards, liquid crystal display devices, lighting fixtures, and thelike, include those fabricated such that a synthetic resin reflectorplate is formed into a three-dimensional shape to thereby yield a lightreflector plate (refer to, for example, Patent Reference 1).

Patent Reference 1: Japanese Patent Laid-Open Publication No.2002-122863

DISCLOSURE OF THE INVENTION

Problems to be Resolved by the Invention

Deformation of the foregoing light reflector plate fabricated by forminga synthetic resin reflector plate into a three-dimensional shape occursafter manufacture due to strain during forming and shrinkage afterforming. Therefore, a proposed means for preventing this deformation ofthe light reflector plate is a means for fixing the reflector plate anda metal casing by providing the light reflector plate with a hole or aslit incision part, as well as forming a claw-shaped folding part on themetal casing, inserting the claw-shaped folding part of the metal casinginto the hole or slit incision part of the light reflector plate, andfurthermore, folding the claw-shaped folding part.

However, the foregoing light reflector plate deformation preventionmeans had demerits in that it was difficult to make the light reflectorplate thin because a metal casing is required and the processing costsfor fixing the light reflector plate and the metal casing was high.

In light of the foregoing issues, an object of the present invention isto provide a technology for effectively preventing deformation of alight reflector plate fabricated by forming a synthetic resin reflectorplate into a three-dimensional shape and, additionally, reducingprocessing costs.

Means of Solving the Problems

In order to achieve the foregoing objective, the present inventionprovides a light reflector plate, composed of a reflector platefabricated by forming predetermined areas of a light-reflecting plasticfilm or sheet into a three-dimensional shape, to which a shape-retentivecomponent is fixed.

In the present invention, a shape-retentive component is fixed to areflector plate which is formed into a three-dimensional shape.Deformation of the reflector plate is prevented by the effect of thisshape-retentive component, and the shape is retained. Therefore, thelight reflector plate can be made thinner compared to when metal casingsare used. In addition, processing costs are reduced compared to fixing alight reflector plate and a metal casing because the present inventionmerely involves fixing the shape-retentive component to the reflectorplate.

EFFECT OF THE INVENTION

According to the present invention, deformation of a light reflectorplate fabricated by forming a synthetic resin reflector plate into athree-dimensional shape can be effectively prevented and, additionally,processing costs can be reduced, lowering costs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an example of an incision processing and anenlarged view of the incisions on a sheet before folding;

FIG. 2 is a perspective view of a light reflector plate using the sheetin FIG. 1;

FIG. 3 is a diagram showing the profile of the light reflector plate inFIG. 2 and the position of the fluorescent light;

FIG. 4 is a rear-surface view of the light reflector plate in FIG. 2;and

FIG. 5 is a perspective diagram showing a sheet forming an arch-shapedprotruding part.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention is described in further detail hereafter. In thepresent invention, for example, general-purpose resins such aspolyethylene, polypropylene, polystyrene, polyvinylchloride (PVC),polybiphenylchloride, polyethylene terephthalate and polyvinyl alcohol,engineering plastics such as polycarbonate, polybuthylene terephthalate,polyamide, polyacetal, polyphenylene ether, ultra-high molecular weightpolyethylene, polysulfone, polyethersulfone, polyphenylenesulfide,polyarlate, polyamideimide, polyetherimide, polyetheretherketone,polyimide, polytetrafluoroethylene, liquid crystal polymer andfluororesin, or copolymers and mixtures thereof are given as materialsfor light-reflecting plastic film or sheet. Of these, due to superiorheat-resistance and impact-resistance properties and the like,polyester, polyphenylenesulfide, polypropylene, and cyclopolyolefin arepreferable. Antioxidant, ultraviolet inhibitor, lubricant, pigment,reinforcement and the like can be added accordingly to the resin used inthe foregoing light-reflecting plastic film or sheet. In addition, acoating layer containing these additives may be applied and formed.

Specifically, preferred examples of the light-reflecting plastic film orsheet include a thermoplastic resin film or sheet having numerous finebubbles or pores with a mean bubble diameter of 50 μm or less, or athermoplastic resin film or sheet containing fillers wherein numerousvoids are formed with the filler as the core. In this case, in thelatter film or sheet, the thermoplastic resin film or sheet containingfillers is preferably a porous stretched film or sheet, wherein numerousvoids are formed with the filler as the core by forming an un-stretchedfilm or sheet containing fillers and stretching this un-stretched filmor sheet.

In the present invention, although there are no limitations to the meansfor forming the reflector plate of light-reflecting plastic film orsheet into a three-dimensional form, preferably, a means forintermittently forming narrow slits which penetrate from the frontsurface of one side to the front surface of the opposite side of thefilm or sheet along a straight line and folding the film or sheet alongthese slits can be implemented.

In other words, although hot-forming can be performed with a mold or thelike in order to process the resin reflector plate into athree-dimensional shape, not only is the processing accuracy poor due toshrinkage after hot-forming, but molds and processing costs areexpensive, as well. On the contrary, by cutting perforation slits intothe plastic film or sheet, it can be easily folded at this section and athree-dimensional shape can be formed accurately, realizing a foldingprocessing with simple jigs and the like at a low cost, without the needfor expensive molds or the like.

In this case, the film or sheet on which slits are formed is preferablythe foregoing thermoplastic resin film or sheet having numerous finebubbles or pores with a mean bubble diameter of 50 μm or less, or athermoplastic resin film or sheet containing fillers wherein numerousvoids are formed with the filler as the core.

In addition, preferably, the width of the slits formed on the plasticfilm or sheet is 3 mm or less, the length of one slit is 10 mm or less,the length of the un-cut section between two adjacent slits is 1 mm ormore. In other words, in order to prevent the material from becomingsevered from the slit part when folding along the perforated line aftercuffing slits into the film or sheet, the un-cut sections between theintermittent slits are preferably 1 mm or more. In addition, withregards to the length of the slit, it is cheap and practical to performprocessing with a standard commercially-sold cutting tool having aperforation cutting blade with a 10 mm pitch or less.

If, rather than cutting slits such as the foregoing into the film orsheet, a concave pressed-line is formed in a straight line on thesurface of the film or sheet and the film or sheet is folded along thisline, this is disadvantageous in that the folding processing isdifficult because the folding force is large and the fold is notnecessarily made at the line part.

In addition, if perforation cutting processing is performed as such in aplastic film or sheet which does not have bubbles, pores or voids, thefilm or sheet may not be equally cut throughout when the perforationcutting part is processed at once because it is hard, if there are manyfolds or the processing area is large (for example, such as in FIG. 1and FIG. 2, described hereafter), and therefore, the film or sheet maynot fold properly along the perforation. On the contrary, becauseplastic film or sheet having bubbles, pores, or voids is soft and easyto cut, it can be cut relatively cleanly, even if there are manyperforations or the area is large.

The preferred shape-retentive component used in the present inventionhas mechanical characteristics preventing the deformation of a lightreflector plate which has been formed into a three-dimensional shape,such as, for example, adhesive tape, cords, pins, or the like. Theshape-retentive component preferably has heat-resistant properties of130° C.

If adhesive tape is implemented as the shape-retentive component, thoughthe base material of the adhesive tape is not limited, polymers such aspolyester, polyolefin, cyclopolyolefin, polyamide, polyarlate,polycarbonate, polyacetal, polyphenylene ether, polymethylpentene, andliquid crystal polymer, or metals such as aluminum and stainless steelcan be given. If a polymer is implemented as the base material of theadhesive tape, polyester, polypropylene, or cyclopolyolefin isparticularly preferable among these, due to favorable heat-resistanceand impact-resistance properties. Furthermore, the adhesive tape ispreferably colorless or white. If the adhesive tape is colored inanother color, this color may appear on a screen when the lightreflector plate is implemented in a liquid crystal display device. Thematerial of the adhesive on the adhesive tape can be selectedaccordingly, taking into consideration the foregoing points.

EXAMPLES

Next, examples of a light reflector plate according to the presentinvention are described with reference to the drawings. However, thepresent invention is not limited to the following examples.

Example 1

There is a foamed plastic light reflector sheet (for example, MCPET(registered trademark), manufactured by Furukawa Electric Co., Ltd) witha thickness of 1 mm and bubbles with a bubble diameter of 50 μm or less,which is a thermoplastic polyester extrusion sheet heated and foamedafter impregnating with carbon dioxide gas under high pressure. Inaddition, there is a cyclopolyolefin foamed plastic light reflector filmwith a thickness of 0.5 mm and bubbles with a bubble diameter of 50 μmor less. When these light reflector sheet and film are incorporated asreflector plates for backlight of a liquid crystal display device, thefollowing example can be given as an example for manufacturing athree-dimensional light reflector plate behind the fluorescent lightwhich is to be the light source of the backlight.

As shown in FIG. 1, perforations 4 were formed linearly using aband-blade press cutting blade with a blade thickness of 0.7 to 1.42 mm,for cutting perforations of 5 mm length intervals into a sheet, on afoamed polyethylene terephthalate sheet 2 (foregoing MCPET) which hadbeen foamed by four-fold, with a thickness of 1 mm and a mean bubblediameter of 50 μm or less. Then, as shown in FIG. 2, a reflector plate 6was obtained by folding the foamed sheet 2 at the perforation parts 4such as to form linear mountain-shapes. The pitch of the foldedmountain-shapes is, as shown in FIG. 3, designed such that the peakparts of the mountains are in a position, P/2, almost midway between thefluorescent lights 8, according to the pitch P of the fluorescent lights8 of the backlight. Molds were not used in the folding processing andthe sheet was folded one mountain at a time using a tool shapedaccording to the mountain/valley shape.

Next, in order to retain the shape of the reflector plate 6, as shown inFIG. 2 to FIG. 4, three strips of adhesive tape 10, perpendicular to theperforation parts 4, were adhered on the back surface of the reflectorplate 6 (opposite surface of the light source 8), from one edge part ofthe reflector plate 6 in the width direction to the other edge part withpredetermined intervals therebetween, thus obtaining the light reflectorplate of the present invention. In this case, the adhesive tapes 10 wereadhered to the reflector plate 6 such as not to apply tension or sag.The light reflector plate of the present example has a plurality ofmountain-shaped protrusion parts 12 along the length direction of thestrip light sources 8 and the shape of the mountain-shaped protrusionparts 12 is retained by the adhesive tape 10.

Comparative Example

A light reflector plate was obtained in the same way as Example 1, asidefrom not adhering adhesive tape to the back surface of the reflectorplate 6. Deformations occurred in this light reflector plate due tostrain during forming and shrinkage after forming.

Example 2

The light reflector plate of the present invention was obtained in thesame way as Example 1, aside from implementing a porous stretched sheetwith a thickness of 0.25 mm, wherein numerous voids are formed withcalcium carbonate as the core by stretching an un-stretched polyethyleneterephthalate sheet containing calcium carbonate (filler), continuouslyforming a cut groove which does not penetrate the surface of the sheeton the sheet along a straight line, folding the sheet along this cutgroove, and adhering adhesive tape to the entire back surface of thereflector plate. The light reflector plate of the present example has aplurality of mountain-shaped protrusion parts along the length directionof the strip light sources and the shape of the mountain-shapedprotrusion parts is retained by the adhesive tape.

Example 3

The light reflector plate of the present invention was obtained in thesame way as Example 1, aside from implementing, as the light reflectorsheet, a combined sheet wherein a porous stretched sheet with athickness of 0.1 mm, wherein numerous voids are formed with calciumcarbonate as the core by stretching an un-stretched polyethyleneterephthalate sheet containing calcium carbonate (filler), is laminatedwith an aluminum sheet. An aluminum sheet was laminated onto thiscombined sheet because the porous, stretched polyethylene terephthalatesheet is thin, has no independence, and cannot retain athree-dimensional shape alone. The light reflector plate of the presentexample has a plurality of mountain-shaped protrusion parts along thelength direction of the strip light sources and the shape of themountain-shaped protrusion parts is retained by the adhesive tape.

Example 4

The light reflector plate of the present invention was obtained in thesame way as Example 1, aside from implementing, as the foamedpolyethylene terephthalate sheet 2 (foregoing MCPET) which had beenfoamed by four-fold, with a thickness of 1 mm and a mean bubble diameterof 50 μm or less, a sheet which had been foamed after fabricating thebase plate 20 of the polyethylene terephthalate sheet, prior to foaming,into a form having curved arch-shaped (semicircular cross-section)protrusion parts 22 by a press, as shown in FIG. 5. The sheet waspressed before foaming because the bubbles will break if the sheet waspressed after foaming. The light reflector plate of the present examplehas a plurality of mountain-shaped protrusion parts along the lengthdirection of the strip light sources and the shape of themountain-shaped protrusion parts is retained by the adhesive tape.

Although three strips of adhesive tape were adhered on the back surfaceof the reflector plate from one edge part of the reflector plate in thewidth direction to the other edge part with predetermined intervalstherebetween or the adhesive tape was adhered on the entire back surfaceof the reflector plate, the number of strips of adhesive tape and themethod of adhering can be set accordingly, so long as deformation of thereflector plate can be prevented by the adhesive tape.

Example 5

The light reflector plate of this example is the same as Example 1,aside from implementing aluminum tape with a thickness of 0.1 mm as theshape-retentive component. The light reflector plate of the presentexample has a plurality of mountain-shaped protrusion parts along thelength direction of the strip light sources and the shape of themountain-shaped protrusion parts is retained by the aluminum tape.

INDUSTRIAL APPLICABILITY

According to the light reflector plate of the present invention, thebacklights and illumination boxes for illumination signboards, liquidcrystal display devices, lighting fixtures and the like can be madebrighter and thinner and illuminated efficiently. In addition, accordingto the present invention, not only can deformation of the lightreflector plate fabricated by forming a synthetic resin reflector plateinto a three-dimensional shape can be prevented effectively and thelight reflector plate can be made thinner, but processing costs can bereduced as well, thereby lowing costs.

1. A light reflector plate, comprising: a light-reflecting plastic filmor sheet including predetermined areas having a three-dimensional shape,the three-dimensional shape being formed of a plurality of parallelprojections such that the film or sheet has a peak-and-valley shape; anda shape-retentive component fixed to an underside of the film or sheetabutting a valley portion of the three-dimensional shape, therebyretaining the three-dimensional shape of the projections.
 2. The lightreflector plate according to claim 1, wherein said light-reflectingplastic film or sheet is a thermoplastic resin film or sheet havingnumerous fine bubbles or pores with a mean bubble diameter of 50 μm orless.
 3. The light reflector plate according to claim 1, wherein saidlight-reflecting plastic film or sheet is a thermoplastic resin film orsheet containing fillers, and wherein numerous voids are formed withsaid filler as a core.
 4. The light reflector plate according to claim3, wherein said thermoplastic film or sheet containing fillers is aporous stretched film or sheet, and wherein the numerous voids areformed with said filler as the core by forming an un-stretched film orsheet containing fillers and stretching said un-stretched film or sheet.5. The light reflector plate according to claim 1, wherein saidreflector plate includes narrow slits disposed along a straight line,the slits penetrating from a front surface of a first side to a frontsurface of a second opposite side of said light-reflecting plastic filmor sheet, and wherein the film or sheet is folded along said straightline of slits.
 6. The light reflector plate according to claim 1,wherein said shape-retentive component is an adhesive tape.
 7. The lightreflector plate according to claim 6, wherein a base material of saidadhesive tape includes at least one of polyester, polypropylene, andcyclopolyolefin.
 8. The light reflector plate according to claim 2,wherein said reflector plate includes narrow slits disposed along astraight line, the slits penetrating from a front surface of a firstside to a front surface of a second opposite side of saidlight-reflecting plastic film or sheet, and wherein the film or sheet isfolded along said straight line of slits.
 9. The light reflector plateaccording to claim 3, wherein said reflector plate includes narrow slitsdisposed along a straight line, the slits penetrating from a frontsurface of a first side to a front surface of a second opposite side ofsaid light-reflecting plastic film or sheet, and wherein the film orsheet is folded along said straight line of slits.
 10. The lightreflector plate according to claim 4, wherein said reflector plateincludes narrow slits disposed along a straight line, the slitspenetrating from a front surface of a first side to a front surface of asecond opposite side of said light-reflecting plastic film or sheet, andwherein the film or sheet is folded along said straight line of slits.